1. Field of the Invention
The present invention relates to a power ratchet assembly, and more particularly to a power ratchet assembly with stabilized crankshaft.
2. Description of Related Art
With reference to FIGS. 4 to 5, a conventional power ratchet assembly comprises a handle (A), a power shaft (B), a sleeve (C), a crankshaft (D), a disc (E), multiple planet gears (F) and a ratchet head device (G).
The handle (A) is hollow and cylindrical and has one end and a recess (A1). The recess (A1) is axially defined in the end of the handle (A) and has an inner surface and a bottom. The power shaft (B) is axially and rotatably mounted in the recess (A1). The sleeve (C) is securely mounted in the inner surface of the recess (A1) and has an inner surface and an inside space.
The crankshaft (D) is cylindrical, is rotatably mounted in the sleeve (C) and has two ends, an outer surface, an engaging section (D1) and an eccentric rod (D3). The engaging section (D1) is defined around the outer surface at one end of the crankshaft (D) and is mounted in the inside space of the sleeve (C). The eccentric rod (D3) eccentrically protrudes from the other end of the crankshaft (40) and out of the recess (A1) of the handle (A).
The disc (E) is mounted around and engages the engaging section (D1), is mounted in the inside space of the sleeve (C) and has an end and multiple pins (E1). The pins (E1) protrude from the end of the disc (E) at intervals and face the bottom of the recess (A1).
The planet gears (F) are respectively and rotatably mounted around the pins (E1). Each planet gear (F) engages the inner surface of the sleeve (C) and the power shaft (B).
The ratchet head device (G) is mounted securely around the sleeve (C), abuts the end of the handle (A) and has a head (G1) and a connecting bearing (G2). The head (G1) has an inner surface. The connecting bearing (G2) is a needle roller bearing, is securely mounted in the inner surface of the head (G1) and around the crankshaft (D) between the eccentric rod (D3) and the disc (E).
However, the conventional power ratchet assembly has some drawbacks as follows:
1. Strong Vibration of the Crankshaft (D):
The crankshaft (D) is supported simply by the connecting bearing (G2). While rotating, the crankshaft (D) will strongly vibrate because of insufficient support. Consequently, the vibrating crankshaft (D) will cause the disc (E), the pins (E1) and the planet gears (F) to vibrate. Vibration causes the planet gears (F) to wear easily, makes noise and also decreases the useful life of the power ratchet assembly.
2. Accumulated Tolerance and Concentricity Tolerance.
The crankshaft (D) and the disc (E) are two individual parts and need to be combined. Therefore, accumulated tolerance and concentricity tolerance between the crankshaft (D) and the disc (E) will occur to cause vibration therebetween. This can not stabilize the crankshaft (D) and decreases useful life of the ratchet assembly.
To overcome the shortcomings, the present invention tends to provide a power ratchet assembly to militate the aforementioned problems.